Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Ari on September 18, 2017, 02:48:58 PM
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I've been working on this problem and after trying to go through it twice I'm still getting the wrong answer. Not quite sure what I'm doing wrong. Can anyone help? Thanks in advance, Ari!
Calculate the amount of heat (in kJ) required to convert 65.6 g of water to steam at 100°C. (The molar heat of vaporization of water is 40.79 kJ/mol.)
Here's what I did:
Q1=65.6g x (4.18)x(100-0)
=27420.8 J or 27.42kJ
Q2=65.6g x (1/18.02) x (40.79)
=148.49kJ
Qtot= 27.42 + 148.49 = 175.9kJ
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Ari,
Appreciate you showing work, but it helps if every quantity has a unit attached to make it a little easier to follow what you did. Your problem doesn't specify an initial temperature. It seems like you are using 0 degrees C, but it's not really clear if this is the value you should be using. From a literal reading of the problem as written, it seems like they want you to determine the amount of energy required to convert 65.6 g of water (at 100 deg. C) to steam (at 100 deg. C), in which case there would be no Q1, only the Q2 value.
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You were right, I wasn't considering that T should be 100-100. Thanks for your help :)